Mantra meditation is used widely in Theravada Buddhism. But, it is different from Transcendental meditation in that the Mantras in Theravada mean something.Mantra in Theravadin Buddhismhttp://www.wildmind.org/mantras/theravada-mantras
Widely used may be an overstatement. and what is meant by mantra meditation within the mantra traditions is not what is meant by what is described in the link.
The mantras commonly used in TM are bija, seeds, mantras, which carry specific vibrations which has specific effects upon the practitioner, and let us not forget that Sanskrit is a sacred language and that the letters and words have sphota, a type of power that become manifest with its proper pronunciation.
When mantras are talked about within most Hindu traditions, it is a different animal than what is talked about in the Kornfeild link.
This being is bound to samsara, kamma is his means for going beyond. -- SN I, 38.
There is freedom from birth, freedom from becoming, freedom from making, freedom from conditioning. If there were not this freedom from birth, freedom from becoming, freedom from making, freedom from conditioning, then escape from that which is birth, becoming, making, conditioning, would not be known here. -- Ud 80
Ar scáth a chéile a mhaireas na daoine.
People live in one another’s shelter.
dheamhan a fhios agam
Damned if I know.